Vacationers at the Florida Coast and at the Great Lakes had a good chance to see a waterspout this season. Because of its close resemblance to a tornado, a waterspout can look really frightening. What makes it so distinctly visible is the column of water that’s hurled upward by the swirling wind.
The National Oceanic and Atmospheric Administration distinguishes between fair weather waterspouts and tornadic ones. Both kinds are produced by temperature differences between the water surface and the atmosphere. Any time cooler air moves over a warmer surface, convection is likely to occur; that is, the air gets a tendency to rise.
At Lake Michigan, for example, the mornings are already quite cool with the mercury in the 50s or lower. Water temperatures are still reaching the 70-degree mark, which is enough to produce the numerous wet funnels that have been sighted. Eastern Florida and the Gulf Coast have had a busy waterspout season, causing the Internet to fill with pictures of truly scary looking funnels.
For the most part, waterspouts are quite harmless because their rotating wind speeds are only in the 30 to 50 mph range. Most of the fair weather waterspouts develop without a thunderstorm and dissipate again within minutes or seconds. Severe thunderstorms, though, can produce the tornadic type, which has the potential to cause harm.
When a waterspout moves onto land, the National Weather Service issues a tornado warning. In those cases, winds up to 100 mph have been measured and boats, houses and cars have been damaged.
The Hawaiian Islands aren’t prone to tornadoes like you see in Oklahoma or Texas, but waterspouts reaching the shores of Kauai have been known to pose a threat to people.
I’ve never seen any reports of waterspouts on Lake Lanier. Theoretically it could happen, though, when the lake water is warmest (right about now) and a cool air mass moves in from the northwest. If you’re on a boat, the wise action is to steer away from the funnel.
Amazingly, a sailing magazine some years ago showed pictures of sailboats intentionally seeking the periphery of Florida waterspouts because the high winds made for great lean angles and challenging wind shears. While these conditions are unlikely in our area, it’s still best to observe troubled weather from a safe distance, and maybe send a photo of it to The Times.
Rudi Kiefer, Ph.D., is a professor of physical science and director of sustainability at Brenau University. His column appears Sundays and at gainesvilletimes.com.